I am using NX11 to create some complex parts containing many drafts. In the image below, the top half is the original draft, which is then mirrored above the centerline in red. When a draft angle of 5 degrees or smaller is used (top picture),the edge of the drafts cuts in two separate ways, while when a draft angle larger than 5 degrees is used (bottom picture), the edge of the drafts both cut in a triangular fashion.

Can anyone explain why this is happening and how to fix it? I am okay with either resolution, as long as both sides are symmetrical. I am not sure if it is just a visual glitch either.